Most modern devices used at home have a capacity ranging from 0.7 to 1.2 kilowatts per hour (kWh). The presence of additional options, for example, convection, grill or others, usually increases the amount of energy consumed by it per unit time: in this case, the microwave power can be from 1.2 to 2 kWh. In this case, the maximum rated power indicated by the manufacturer corresponds to operation at the extreme position of the power controller: accordingly, the choice of a more economical mode will ensure less energy consumption per unit of time.
The total amount of electricity consumed by a particular device for a certain period of time, for example a month, depends on its nominal capacity, usage mode and the amount of time it was used.
So, you can calculate the energy consumption of a microwave oven by a simple example. Let a particular device have a maximum power equal to 1 kWh, but the owners use it primarily in a more economical mode, which “eats” 0.85 kWh of electricity.
If the microwave is used mainly for heating food, it takes about 40 minutes a day. With daily use, the total operating time per month is 1200 minutes, that is 20 hours. Consequently, the total amount of energy consumed per month is 17 kW.